Question: What do the following two equations represent? $-3x-y = 3$ $3x-9y = -2$
Explanation: Putting the first equation in $y = mx + b$ form gives: $-3x-y = 3$ $-y = 3x+3$ $y = -3x - 3$ Putting the second equation in $y = mx + b$ form gives: $3x-9y = -2$ $-9y = -3x-2$ $y = \dfrac{1}{3}x + \dfrac{2}{9}$ The slopes are negative inverses of each other, so the lines are perpendicular.